The inventive concepts described herein relate to an EEROM (Electrically Erasable Programmable Read-only Memory) cell, and more particularly, relate to an EEROM cell including transistor elements having a uniform thickness and an EEROM device.
EEPROM may be a kind of programmable read only memory (PROM), and may be implemented to overcome such a disadvantage of an erasable programmable read only memory (EPROM) that contents stored therein are erased by exposing it to strong ultraviolet light source. Data stored in the EEPROM may be erased by forcing an electric signal to a pin of a chip.
As a nonvolatile memory device, such an EEPROM may be applied to a system on chip, an RFID (Radio Frequency Identification) tag, and so on. The EEPROM may have various storage capacities ranging from dozen of bytes to several gigabytes according to the use. In the event that the EEPROM is used for the RFID, a superior adhesive strength may be required. For this reason, there may be required high-density and small-sized EEPROMs.
A tunneling insulation film (e.g., a tunneling oxide film) of the EEPROM may be formed to be thicker than about 70 angstroms. Thus, there need be reduced a thickness of the tunneling insulation film for a high-density and small-sized EEPROM. Also, there need be integrated thicknesses of tunneling insulation films of elements constituting EEPROM cells.